21353471 has 4 divisors (see below), whose sum is σ = 21429744. Its totient is φ = 21277200.

The previous prime is 21353461. The next prime is 21353491. The reversal of 21353471 is 17435312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21353471 - 2¹⁴ = 21337087 is a prime.

It is a super-3 number, since 3×21353471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21353471.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21353401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37715 + ... + 38276.

It is an arithmetic number, because the mean of its divisors is an integer number (5357436).

Almost surely, 2^21353471 is an apocalyptic number.

21353471 is a deficient number, since it is larger than the sum of its proper divisors (76273).

21353471 is an equidigital number, since it uses as much as digits as its factorization.

21353471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76272.

The product of its digits is 2520, while the sum is 26.

The square root of 21353471 is about 4620.9816056764. The cubic root of 21353471 is about 277.4317490350.

Adding to 21353471 its reverse (17435312), we get a palindrome (38788783).

The spelling of 21353471 in words is "twenty-one million, three hundred fifty-three thousand, four hundred seventy-one".